We propose pilot exploration of levetiracetam as an adjunctive agent in patients with bipolar illness who are inadequately responsive to routine psychopharmacological agents for bipolar illness. At the NIMH we will study a maximum of 10 acutely depressed, 10 manic, and 10 cycling patients enrolled in Protocol 97-M-0039. We would start at Levetiracetam doses of 500 mg/day, and not to exceed 4000 mg/day. Response will be based primarily on the percentage of patients showing "much" or "very much" improvement on the GCI-BP score in each of the three groups as augmented by the percentage decrement on cross-sectional scales such as the Inventory of Depressive Symptomatology (IDS) and Young Mania Rating Scale (YMRS) in conjunction with prospective ratings on the NIMH-LCMp. Should preliminary evidence of efficacy be observed in this open add-on clinical trial, more systematic controlled studies will then be designed for confirmation of promising target areas of efficacy.